You can use a live backup to provide a redundant copy of the transaction log that is available for restart of your system on a secondary computer in case the computer running the database server becomes unusable.
A live backup runs continuously, terminating only if the server shuts down. If you suffer a system failure, the backed up transaction log can be used for a rapid restart of the system. However, depending on the load that the server is processing, the live backup may lag behind and may not contain all committed transactions.
An alternative to a live backup is to use database mirroring. See Introduction to database mirroring.